Speaker device



W. A- PAVLAK SPEAKER DEVICE Nov. 27, 1962 2 Sheets-Sheet 1 Filed Aug.11, 1958 INVENTOR. Walter Alexander Povlak BY M yMwYa Md% ATTORNEYS Nov.27, 1962 w. A. PAVLAK 3,066,200

SPEAKER DEVICE Filed Aug. 11, 1958 2 Sheets-Sheet 2 FIG? - INVENTOR. nWalter Alexander Pavlok Q 8 g wiwmww ATTORNEYS United States Patent3,066,200 SPEAKER DEVICE Walter A. Pavlak, Newark, N..I., assignor toWilliam Ward Jackson, Short Hills, NJ. Filed Aug. 11, 1958, Ser. No.754,449 8 Claims. (Cl. 179--115.5)

My invention relates to the transmission and reproduction of sound andin particular provides a transducer for converting sound into electricalsignals or for converting audio frequency electrical signals into sound.The transducer of my invention is thus useful as a microphone, earphoneor a loudspeaker.

In the reproduction of sound and particularly in reproducing music it isof course highly desirable to provide a speaker not only capable ofreproducing the original sound without distortion but also having afrequency response extending throughout the audible range. Heretofore ithas generally been necessary to provide a plurality of speaker devicesfor different portions of the audio frequency range in order that theentire audible range will be accurately reproduced. Such plural speakersystems nesessarily involve mechanical or electrical frequencycross-over devices for separating the original sound into the variousfrequency ranges to be reproduced by the individual speaker units. As aconsequence, highly complicated and expensive speaker systems arerequired for obtaining so-called high fidelity" sound reproduction. Moreparticularly in the reproduction of sound by the so-called binauralsystem two separate speaker systems must be employed thus doubling theamount of equipment necessary for high fidelity reproduction. Manytimes, moreover, it is desirable to provide good quality soundreproduction under circumstances interfering with the activities ofothers. At present the employment of earphones to prevent suchinterference is unsuitable where high fidelity reproduction is requireddue to the high cost of providing the plural earphone system necessaryto obtain full audio frequency range reproduction.

It is a principal object of my invention to provide a simple speakerdevice for reproducing electrical signals as sound having a widefrequency response range extending throughout the principal audiblerange. It is also an object of my invention to provide such a speakerdevice which can be constructed in a relatively small space such that itcan be suitably employed as an earphone. It is still a further object ofmy invention to provide a speaker device which is simple in mechanicalconstruction and which can be connected directly to the output of anaudio amplifier without the employment of electrical or mechanicalcross-over networks. It is yet another object of my invention to providesuch a speaker device which is inexpensive to manufacture and which isextremely light in weight.

While the general object of my invention is to provide a speaker devicefor reproducing sound, the same device with minimum modificationprovides an excellent microphone for faithfully converting soundextending throughout the principal audible range into electrical signalswhich can be simply connected to the input of an audio amplifier,recording equipment or other conventional devices.

In keeping with these general purposes my invention thus provides aspeaker device which can suitably be employed for high fidelity soundreproduction. In pairs, such speakers can be employed for binaural soundreproduction when connected to separate amplifiers. Simulated binauraleffects can be developed employing a pair of such speaker devices asearphones where a capacitance is included in one of the earphones topermit control of the bass and treble response in such earphones. Aswill be evident later, the speaker device of my invention can ice alsobe constructed to provide a limited frequency range accentuating thetreble response or bass response as desired. Thus, simulated binauraleffects can be obtained employing one earphone constructed to emphasizethe bass frequency range of the music and one constructed to emphasizethe treble range. It is also possible, employing the speaker device ofmy invention in multiples, to provide a thin loudspeaker which can behung against a wall. A picture frame" speaker, thus constructed usingthe device in multiples, can be provided having a thickness of one inchor less and which is capable of reproducing faithfully the originalsound throughout the audible range.

These and other objects of my invention which will become more apparenthereinafter are essentially obtained by positioning a pair of magnetsspaced from each other such that a pole face of one and a pole face ofthe second having opposite polarity lie in a common plane spacedslightly from each other to define an elongated narrow magnetic gap. Athin diaphragm of non-magnetic material is supported extended across andalong the magnetic gap in a free floating position, and an elongatedconductor is affixed to the diaphragm extending lengthwise of the gapbetween the two pole faces.

When the speaker is to be employed for sound reproduction the ends ofthe conductor are connected to a conventional low impedance output of anaudio amplifier such that electrical output signals of the amplifier arepassed through the elongated conductor to cause the conductor togetherwith the diaphragm to which it is affixed to vibrate toward and awayfrom the magnetic gap corresponding such electrical output signals. Themovement of the diaphragm thus sets up sound waves reproducing theoriginal sound used to generate the signals in the amplifier.

When the speaker device of my invention is to be employed for soundtransmission, however, the ends of the conductor are connected insteadto a conventional low impedance input of an audio amplifier. Thus, whenthe diaphragm is vibrated by sound waves which impinge against it, themovement of the elongated conductor in the magnetic gap generateselectrical currents in the conductor which correspond to the impingingsound waves and are coupled to the input of the amplifier to drive theamplifier.

In a more specific aspect I employ a system of magnets arranged toprovide a plurality of such magnetic gaps extending parallel to eachother and arrange the conductor, as it leaves one gap, to turn on itselfand enter the next adjacent gap, thus permitting the employment. of arelatively square or round diaphragm of which almost every portion isactuated simultaneously by movement of the conductor under the influenceof the application of electrical signals.

In another aspect, particularly where the speaker device of my inventionis employed as a microphone, I have found it advantageous to provide asecond pair of magnets similarly spaced from each other, such that apole face of one and a pole face of a second having opposite polaritylie in a common plane spaced slightly from each other to define a secondelongated narrow magnetic gap. The second pair of magnets is positionedconfronting the first pair of magnets with pole faces of like polarityspaced closely together. Thus, the two elongated narrow magnetic gapsconfront each other with their magnetic force lines lying in the samedirection. The diaphragm is supported extended across the two gaps andlengthwise between the confronting pole faces of the two pairs ofmagnets with the elongated conductor extending lengthwise between thetwo confronting magnetic gaps. This arrangement is possible because,surprisingly, accuratereprodnction can be obtained if the diaphragm isoriented such that the sound waves which are to be converted toelectrical signals are directed into the speaker device edgewise of thediaphragm.

For a more complete understanding of the practical application of theprinciples of my invention, reference is made to the appended drawingsin which:

FIGURE 1 is a diagrammatic illustration of the underlying principle ofoperation employed in my speaker;

FIGURE 2 is a cross-section through a practical construction embodyingthe principles of my invention to provide an earphone type speaker;

FIGURE 3 is a section taken at line 3-3 in FIGURE 2;

FIGURE 4 is an exploded view of a portion of the device shown in FIGURES2 and 3;

FIGURE 5 is an exploded view of another device constructed in accordancewith the principles of my invention;

FIGURE 6 is an elevational view of the assembled construction of FIGURE5; and

FIGURE 7 is a cross-section taken at line 7-7 in FIG- URE 6.

Referring more particulary to FIGURE 1, the reference numeral 10indicates the basic device of my invention which is schematically shownconnected to the output transformer 11 of a typical conventional audioamplifier. Speaker device 10 basically includes a pair of bar magnets 12and 13 constructed to any suitable magnetic substance having highcoercive force and rententivity such as Alnico No. S.

Magnets 12 and 13 are erected on a suitable fiat surface 9 to which theyare afiixed to hold them parallel and spaced a short distance from eachother with the south pole face 12a on the upper side of magnet 12 andwith the north pole face 13a on the upper side of magnet 13. Thus attheir upper ends, magnets 12 and 13 define an elongated narrow magneticgap 14.

Four non-magnetic posts 15 affixed at their lower ends 0 on surface 9are erected with one post 15 adjacent each outer corner of therectangular solid space occupied by magnets 12 and 13. Posts 15 haveapproximately the same height as magnets 12 and 13 and at their upperends carry short cushions 16 of sponge rubber or similar relativelyelastic and freely compressed and stretched material. Cushions 16 arecemented at their lower ends to the upper ends of posts 15 and extendslightly above the pole faces 12a and 13a.

The thin diaphragm 17, in the illustrated case of rectangular shape, ispositioned horizontally above the upper ends 12a and 13a of magnets 12and 13 and is cemented at its corners on the upper ends of cushions 16which thus support diaphragm 17 spaced slightly above the upper ends 12aand 13a of magnets 12 and 13 with diaphragm 17 extended across and alongmagnetic gap 14. Diaphragm 17 is constructed typically of polyvinylchloride sheet material but can be made of almost any non-magneticmaterial such as wood, paper, cloth, glass or the like. The material ofconstruction of diaphragm 17 can be either soft or hard, it can berelatively elastic or relatively inelastic, it can be freely flexible orit can be quite stiff. Depending upon the variations of thesecharacteristics different frequency response patterns can be obtained. A

v treble response is accentuated by harder, more inelastic and stiffermaterials, while bass response is accentuated by softer, relatively moreelastic and flexible material.

A ribbon conductor 18 is cemented to the upper surface of diaphragm 17and extends lengthwise over gap 14. Preferably conductor 18 has the flatribbon-shaped appearance shown in FIGURE 1 and is aligned along itsedges with the adjacent edges of the upper surfaces 12a and 13a ofmagnets 12 and 13 between which magnetic gap 14 is defined. Theemployment of a fiat ribbon type conductor is not essential, however,and wire conductors can also be employed, however with less efiiciency.Condoctor 18 in the illustrated case is a strip of aluminum foilcemented to diaphragm 17. It, however, obviously can be applied todiaphragm 17 in the same manner as 4 printed circuits are manufactured;it can be heat-sealed between a pair of thin sheets of material fromwhich diaphragm 17 is constructed, and it can be applied in otherobvious ways.

The ends of conductor 18 are connected to flexible electrical lead wires19 and 20 which connect conductor 18 in series with the low impedancesecondary winding 11a of output transformer 11. The impedance of winding11a is not particularly critical and typically will range up to severalhundred ohms but typically will be on the order of 2 to 8 ohms.

In operation where transformer 11 is the output transformer of anamplifier connected to a source, such as a phonograph, providingelectrical signals in the audio frequency range, the sound is reproducedby vertical vibration of diaphragm 17 as conductor 18, by reason of thepassage of electrical current through it, is caused to move verticallyin magnetic gap 14. It will be selfevident that the closer to gap 14that conductor 18 is positioned, the lesser the distortion introducedwill be. However, conductor 18 is limited in its position relative togap 14 by the fact that diaphragm 17 must have room to vibrate freely.Alternatively, transformer 11 can be an input transformer of aconventional audo amplifier, in which case winding 11a will be theprimary winding and typically will have a relatively low impedance. Inthe latter case, sound impinging against diaphragm 17 will causevibration of conductor 18 vertically in magnetic gap 14. This movementwill generate electric currents in conductor 18 which, being coupled byleads 19 and 20 to primary winding 11a of transformer 11, will drive theaudio amplifier to which transformer 11 is connected. Thus soundstriking diaphragm 17 Will be reproduced as an electric signal which canbe utilized to drive conventional audio equipment.

FIGURES 2, 3 and 4 illustrate a practical arrangement of a speakerconstructed in accordance with my invention, having particular utilityas an earphone. In FIGURES 2, 3 and 4 the earphone of my invention isdesignated basically by the reference numeral 30 and is suitably housedin a short cylindrical casing 31 having one end closed by an integralbottom 32 and externally threaded at the other end as indicated by thereference numeral 33. A perforated cap 34 is threadedly engaged withcasing 31 received on threads 33 to close the housing of ear- 6 phone30. Casing 31 and cap, i.e., earpiece 34 are suitably constructed ofhard plastic material such as a phenolic resin or other suitablenon-magnetic material.

Casing 31 contains a modified version of speaker device 10 providing apreferred construction for obtaining maximum efiiciency in soundreproduction while at the same time obtaining full frequency rangeresponse. To be more specific, casing 31 is provided with a system 36of'U-shaped, i.e. channel shaped, magnets 35 which, as seen more clearlyin FIGURE 4, are disposed in staggered arrangement to define eightelongated narrow magnetic gaps 37 of the type denoted by referencenumeral 14 in FIGURE 1.

The magnet system 36 is thus composed of twentyeight identicalchannel-shaped magnets 35 arranged in seven parallel rows with fourmagnets in each row. In each row the four magnets 35 are disposed in aline presenting alternating north pole faces 35a and south polefaces-35b. The four magnets 35 in each row are spaced from each other adistance identical to the spacing of the opposite pole faces 35a and 35bof each individual magnet 35. The seven rows of magnets, as indicatedabove, are parallel and each adjacent pair of rows are arranged withtheir respective magnets closely adjacent but staggered lengthwise suchthat in any given pair of adjacent rows of magnets the channel centersof the magnets 35 in one row register with the spaces between magnets inthe other row. In each adjacent pair of rows, however, the pole faces ofthe magnets are aligned. Accordingly,

the magnets in each adjacent pair of rows are disposed in reversedorders of polarity. In any adjacent pair of rows of magnets, the poleface of a magnet in one row adjacent the pole face of another magnet inthe second row are not only aligned but have identical polarity. Thus,the magnet system 36 includes parallel lines of pole faces 35a and 35bwhich define between them eight elongated parallel magnetic gaps 37extending perpendicularly to the parallel rows of magnets 35. Along oneside of each gap 37, magnets 35 all present their north pole faces 35a,and along the other side of each gap 37, magnets 35 all present theirsouth pole faces 35b.

The system 36 of magnets 35 is maintained in position on a brass plate38 (see FIGURE 2) to which magnets 35 are affixed on their under sidesby means of small machine screws 39. Plate 38 also supports four diaphragm support posts 40 which on their under ends (in FfGURE 2) aresimilarly aflixed to brass plate 33 by means of small machine screws 41.Posts 40 are identical in height with magnets 35, and on their upperends are provided with short sponge rubber cushions 42. Posts 40 are,moreover, located at the four corners of the space occupied by magnetsystem 36 and are constructed of non-magnetic material, such aspolystyrene rod.

A diaphragm 43 of generally rectangular shape provided with corner ears44 (see FIGURES 3 and 4) is positioned across magnet system 36 abovepole faces 35a and 35b and gaps 37 with cars 44 resting on cushions 42to which diaphragm 43 is cemented to retain it in position. Diaphragm 43supports a flat metallic ribbon conductor 45 which is cemented on theupper surface of diaphragm 43 following a tortuous path including eightparallel straight portions 45a which are aligned over gaps 37 and whichare inter-connected at alternate pairs of adiaccnt ends by connectingportions 45b. Thus the instantaneous electrical current flowing in agiven direction through conductor 45 is flowing in alternatingdirections in adjacent straight portions 45a. The free ends of conductor45 are electrcally and mechanically connected to flexible lead wires 46and 47, which terminate with conventional lugs 48 and 49, respectively,for connections to the output of an audio amplifier.

The assembly of base plate 38, magnet system 36, diaphragm 43 andconductor 45 is positioned in the bottom 32 of casing 31 with base plate38 resting against bottom 32 to which it is secured by means of screws50, thus positioning diaphragm 43 adjacent the threaded end 33 of casing31 over which perforated cap 34 is positioned. Leads 46 and 47 arebrought through suitable insulated bushings 51 and 52, respectively,mounted in the side Wall portion of casing 31.

In operation, lugs 48 and 49 are connected to the low impedance outputof an audio amplifier in a conventional manner and earphone 30 ismounted in a head set, for example, by providing center bored bosses 53on the exterior of casing 31 for receiving the pivot pins of the headset.

In a construction typified by FIGURES 2, 3 and 4 employing twenty-eightchannel shaped Alnico No. 5 magnets ,5,, inch high, M inch across thepoles and inch lengthwise of the gap with gap 37 & inch wide, in whichthe seven rows of magnets are spaced slightly to provide a gap 37 lengthof 2.3 inches, where diaphragm 43 was constructed of soft pliablepolyvinyl chloride having a thickness of 0.0005 inch, in which conductor45 is cut from equal thickness of aluminum foil exactly equal in widthto the gap Width and in which diaphragm 43 was positioned one-eighthinch above the upper faces 35a and 35b of magnets 35, the earphone 30driven by an 8 ohm tap on the output transformer of a conventional 10Watt amplifier gave uniform reproduction throughout a frequency range of40 to 12,000 cycles per second, With some attenuation below and abovethat range.

It should be pointed out that it is highly essential that diaphragm 43be floated. Damping is undesirable and accordingly, as illustrated, thediaphragm is mounted on sponge rubber cushions. Any other type ofdiaphragm mounting which would provide a minimum of damping effectcould, of course, be substituted. Small strips of plastic or fabriccould obviously be employed. The housing is unessential from anacoustical standpoint, but of course is desirable in order to present aneat and attractive device and also in order to prevent damage to thedelicate diaphragm employed. The housing suitably is constructed of anon-magnetic material to simplify problems of insulation and disturbancewith the electrical circuit. The conductor for the same reason should beconstructed of non-magnetic conductor material such as aluminum orcopper.

As indicated above, variation in the material of construction of thediaphragm can be employed to produce varied frequency responses. Thesoft, pliable polyvinyl chloride sheet described above gives an overallwide frequency response. Stiller materials, having harder surfaces, suchas cellulose acetate sheet, will tend to give a response peaked in thetreble range, While softer materials, on the other hand, will tend toemphasize bass response.

Also as indicated above, the speaker device of my invention haspractical utility as a microphone, as, for example, illustrated inFIGURES 5, 6 and 7. Referring to these figures, the reference numeral 60designates a microphone which has been constructed in accordance with myinvention, and which includes fundamentally a first magnet system 61, adiaphragm 62 including an imbedded conductor 63, and a second magnetsystem 64.

Magnet system 61, as is seen more clearly in FIGURE 5, is composed oftwenty-eight channel-shaped magnets 65 disposed in seven parallel rowsof four in a manner identical to the disposition of magnets 35 in magnetsystem 36 described with reference to FIGURES 2, 3 and 4, and thusdefining eight parallel elongated narrow magnetic gaps 66. Along oneside of each gap 66 magnets 65 all present their north pole faces 65a,and along the other side of each gap 66 magnets 65 all present theirsouth pole faces 65b. Magnet system 61 is secured to a circular brassdisk 67 by means of small machine screws 68 in the same manner asmagnets 35 are secured to brass base plate 68 of earphone 30.

Magnet system 64 is composed of twenty-eight channel-shaped magnets 69which are disposed in seven parallel rows of four in a manner exactlycomplementary to magnet system 61, such that when the two magnet systemsare presented in a position confronting each other, a magnet 65confronts each magnet 69 with the north pole face 65a of each magnet 65confronting the north pole face 69a and with the south pole face 65b ofeach magnet 65 confronting the south pole face 69b of a magnet 69.Similarly, the eight parallel elongated narrow magnetic gaps 70 definedby magnets 69 thus can be presented confronting and aligned with theeight magnetic gaps 66 of magnet system 61 with the lines of force ofmagnetic gaps 70 running in the same alternate directions as the linesof force of magnetic gaps 66. Magnet system 64 is similarly affixed to acircular brass plate 71 by means of small machine screws 72.

Diaphragm 62 includes two sheets 73 and 74 of soft, pliable filmmaterial such as saran, cut to identical shape and size. Each sheet 73,74 is thus generally rectangular, having dimensions slightly greaterthan the width and breadth of complementary magnet systems 61, 64. Ateach corner sheets 73, 74 are provided with small extensions or tabsdenoted by the reference numerals 73a. 73b, 73c, 73d in the case ofsheet 73, by the reference numerals 74a, 74b, 74c, 74d in the case ofsheet 74.

Conductor 63 consists of a fiat ribbon of aluminum foil including eightparallel straight lengths 63a interconnected in series by sevenconnecting strips 63b which connect alternate pairs of ends of straightportions 63a. The free ends of conductor 63 are electrically andmechanically connected to flexible lead wires 75, 76 which terminatewith conventional lugs 77, 78, respectively, for connection to the inputterminals of an audio amplifier.

Conductor 63 is assembled with diaphragm 62 by first cementing conductor63 to the face of one sheet 73, 74 with straight portions 63a parallelto one pair of opposite sides of the sheet and with connecting portions63b closely adjacent the other pair of opposite sides of the sheet. Thesecond sheet 73, 74 is then cemented to the first sheet on whichconductor 63 has been previously cemented, so that conductor 63 issandwiched between sheets 73, 74 and so that sheet 73, 74 are perfectlyaligned with tabs 73a, 73b, 73c, 73d being aligned with tabs 74a, 74b,74c, 74d. Each straight portion 63:: of conductor 63 is slightly longerthan magnetic gaps 66, 70 and is slightly narrower than such gaps.Straight portions 63a are, moreover, spaced exactly as magnetic gaps 66,70 are spaced in their respective magnet system 61, 64.

Microphone 60 is assembled by means of four posts 79, four posts 80,four sponge rubber cushions 81, four sponge rubbercushions 82 and twospacer tubes 83. Posts 79 are constructed of non-magnetic material suchas polystyrene, brass or the like, and have a length exactly equal tothe height of each magnet 65 (measured from the pole faces to theopposite face of the channel portion connecting the poles). Posts 79 aresecured to brass plate 67 by means of small machine screws 84 justbeyond the four corners of magnet system 61 such that the ends of posts79 remote from brass plate 67 lie in approximately the plate of polefaces 65a, 65b. Cushions 81 are then cemented on such ends of posts 79,and diaphragm 62, previously assembled with conductor 63 as describedabove, is then positioned with tabs 73a, 73b, 73c, 73d resting againstcushions 81 to which the tabs are thereupon cemented. In such operationof assembling diaphragm 62, care should be taken that each straightportion 63a of conductor 63 is centered 1 lengthwise over a magnetic gap66 with connecting portions 63b lying just beyond the ends of gaps 66.

Posts 80 are similarly of non-magnetic material and approximately equalmagnets 69 in height. Posts 80 are secured to base plate 71 similarlyadjacent the four corners of magnet system 64 and carry cushions 82cemented to their outer ends which lie approximately in the plane ofpole faces 69a, 6%. Base plate 71, with magnet system 64, posts 80 andcushions 82, is then positioned on the side of diaphragm 62 oppositemagnet system 61 with cushions 82 being cemented to diaphragm 62 at tabs74a, 74b, 74c, 74d, and with magnet system 64 exactly aligned withmagnet system 61 such that pole faces 69a confront pole faces 65a, polefaces 69b confront pole faces 65b and magnet gaps 70 confront magneticgaps 66. Thus, diaphragm 62 is positioned floating on cushions 81 and82in the narrow space between the confronting magnetic systems 61, 64.

Since cushions 81 and 82 do not hold the assembly rigid, spacer tubes 83are providedto secure base plate 67 to base plate 71. Thus, spacer tubes83 are preferably constructed of non-magnetic material, such as brass,and have a length equal to the combined lengths of a post 79, a cushion81, a cushion 82 and a post 80, plus the thickness of diaphragm 62.Spacer tubes 83 are positioned between plates 67 and 71 on oppositesides of magnet systems 61, 64 slightly beyond the edges of diaphragm62, and are held in place by means of rivets 85.

The assembled microphone 60 desirably can be encased with copper orother non-magnetic wire mesh and is provided with suitable externalmountings as desired. It will be apparent that sound passing betweenside plates 67, 71 of microphone'60 will cause vibration of diaphragm 62and consequently cause conductor 63 to move laterally through the fieldsof force set up by confronting magnetic gaps 66, 70. Thus, electriccurrents will be generated in straight portions 63a of conductor 63which will have the same instantaneous polarity in conductor 63 becauseof the alternate directions of flux in adjacent gaps 66 and theirconfronting adjacent gaps 70, and be cause of the alternate endconnections 6312. Accordingly, currents generated in conductor 63 bymovement of diaphragm 62 will produce an electric signal at lugs 77, 78,which, when connected to a suitable low level, low impedance input of anaudio amplifier, can be utilized to drive the amplifier.

In a microphone having the same general magnet dimensions describedabove with respect to earphone 30, and also having the samediaphragm-to-magnet spacing, as in the case of earphone 30, apro-amplifier of the type employed with reluctance-type phonographcartridges will generally be required, however preferably withoutequalization normal required in such pre-amplifiers to compensate forbass attentuation and treble emphasis usually employed in phonographrecording.

I claim:

1. A transducer which includes a first magnetized body defining a firstpole face, a second magnetized body defining a second pole face ofpolarity opposite that of said first pole face, said first and secondmagnetized bodies being disposed with said first and second pole facesspaced apart and extending adjacent each other in a common planedefining an elongated, narrow magnetic gap with said first and secondmagnetized bodies disposed to one side of said common plane, a thindiaphragm of non-magnetic material, means supporting said diaphragm infioating position extended across and along said gap on the other sideof said common plane and spaced a short distance from said pole faces,and an elongated conductor positioned entirely on said other side ofsaid common plane extended lengthwise of said gap aliixed between saidpole faces to said diaphragm.

2. A transducer according to claim 1 in which said magnetized bodiesconstitute opposite end portions of a channel-shaped magnet.

3. A transducer according to claim 1 further includes a third magnetizedbody defining a third pole face of the same polarity as said first poleface, and a fourth magnetized body defining a fourth pole face of thesame polarity as said second pole face, said third and fourth magnetizedbodies being disposed spaced a short distance from said diaphragm on theside of said diaphragm opposite said first and second magnetized bodieswith said third pole face confronting said first pole face, with saidfourth pole face confronting: said second pole face, and with said thirdand fourth pole faces spaced apart and extending adjacent each other ina second common plane defining a second elongated, narrow magnetic gapconfronting said first namedgap, said conductor being positionedentirely on the-side of said second common plane remote from said thirdand fourth magnetized bodies.

4. A transducer which includes a plurality of magnetized bodies, eachdefining a pole face, said plurality of magnetized bodies being disposedwith their respective pole faces parallel, spaced apart and extendingadjacent each other in a common plane with said magnetized bodiesdisposed to one side of said common plane, said pole faces being ofalternating polarity thereby defining a plurality of parallel,elongated, narrow magnetic gaps, a thin diaphragm of non-magneticmaterial, means supporting said diaphragm in floating position extendingacross and along said gaps on the other side of said common plane andspaced a short distance from said pole faces, and an elongated conductorpositioned entirely on said other side of said common plane afiixed tosaid diaphragm including a plurality of straight portions each extendinglengthwise of one said magnetic gap between the adjacent pole facesdefining said one gap and a plurality of end connections seriallyconnecting alternate pairs of adjacent ends of said straight portionswhereby said straight portions are interconnected in series.

5. A transducer according to claim 4 in which said magnetized bodiesconstitute opposite end portions of a plurality of channel-shapedmagnets.

6. A transducer according to claim 4 in which said conductor is ribbonshaped.

7. A transducer which includes a first magnetized body defining a firstpole face, a second magnetized body defining a second pole face ofpolarity opposite that of said first pole face, a third magnetized bodydefining a third pole face of the same polarity as said first pole face,and a fourth magnetized body defining a fourth pole face of the samepolarity as said second pole face, said first and second magnetizedbodies being disposed with said first and second pole faces spaced apartand extending adjacent each other in a common plane defining anelongated, narrow magnetic gap with said first and second magnetizedbodies disposed to one side of said common plane, a thin diaphragm ofnon-magnetic material, means supporting said diaphragm in floatingposition extended across and along said gap on the other side of saidcommon plane and spaced a short distance from said pole faces, saidthird and fourth magnetized bodies being disposed spaced a shortdistance from said diaphragm on the side of said diaphragm opposite saidfirst and second magnetized bodies with said third pole face confrontingsaid first pole face, with said fourth pole 'face confronting saidsecond pole face, and with said third and fourth pole faces spaced apartand extending adjacent each other in a second common plane defining asecond elongated, narrow magnetic gap confronting said first named gap,and an elongated fiat conductor positioned entirely between said firstnamed and said second common planes extending lengthwise of said gapsafiixed between said pole faces to said diaphragm.

8. A transducer which includes a plurality of magnetized bodies eachbeing respectively disposed with a pole face parallel with a pole faceof each of said magnetiezd bodies in a common plane, said magnetizedbodies being disposed on one side of said common plane, the pole facesin said common plane being disposed adjacent and spaced apart in pairsof opposite polarity, said pairs of pole faces each definingtherebetween one of a p1urality of elongated, narrow, magnetic gaps, athin diaphragm of non-magnetic material, means supporting said diaphragmin suspended position extending across and along said gaps on the otherside of said common plane and spaced a short distance from said polefaces, a plurality of fiat conductors contacting with and afiixed tosaid diaphragm and lying in a plane parallel thereto also positionedentirely on the other side of said common plane, each conductorextending lengthwise of one of said magnetic gaps between one of saidpairs of adjacent pole faces, a first terminal and a second terminal,each of said conductors having a first end and a second end, saidconductors being interconnected between said first terminal and saidsecond terminal, said first end of each of said conductors beingconnected in closer electrical relationship to said first terminal, andsaid second end of each of said conductors being connected in closerelectrical relationship to said second terminal, the orientation of eachof said conductors and the pair of magnetized bodies associatedtherewith in respect of said first end and said second end of saidconductor and in respect of the polarity of each of said pair ofmagnetized bodies associated therewith, being identical as viewed from apoint on a normal to said common plane.

References Cited in the tile of this patent UNITED STATES PATENTS496,602 Field May 2, 1893 1,523,540 Hecht Jan. 20, 1925 1,542,922Thompson June 23, 1925 1,604,532 Riegger Oct. 26, 1926 1,704,511 NakkenMar. 5, 1929 1,815,564 High July 21, 1931 2,360,796 Roberton Oct. 17,1944 2,404,798 Harry et a1 July 30, 1946 2,545,007 Schultheis Mar. 13,1951 FOREIGN PATENTS 484,339 Germany July 30, 1924 Disclaimer3,066,200.-Walter A. Pavlaic, Newark, NJ. SPEAKER DEVICE. Patent datedNov. 27, 1962. Disclaimer filed Aug. 23, 1966, by the assignee, WilliamWaml Jackson; the inventor assenting.

Hereby enters this disclaimer to claims 3 and 7 of said patent.

[Ofiicial Gazette October 4,1966]

